In recent years, display devices in which the RGBW system is adopted have been developed. Display devices with the RGBW system have pixels which are each made up of a red (R) subpixel, green (G) subpixel, blue (B) subpixel, and a white (W) subpixel. Luminance is improved by the W subpixel, so the luminance of a backlight which lights a liquid crystal panel from behind can be reduced, for example. The reduction of the luminance of a backlight reduces the power consumption of an entire display device.
With the above display device, however, image quality may degrade especially on a gradation screen or the like. Accordingly, the following technique is proposed in order to prevent image quality degradation, for example. A random number sequence is convoluted into a luminance variable to generate a random number, convoluted luminance variable. This random number convoluted luminance variable is convoluted into an image signal to generate a random number convoluted image signal.
See, for example, Japanese Laid-open Patent Publication No. 2013-195784.